The present invention relates to multi-layered filter media and more particularly to a unique and novel arrangement for further improving the construction and particulate removal performance efficiency of multi-layered filter media.
The present invention comprises still another efficient and economical layered filter media arrangement such as disclosed in recently issued U.S. Pat. No. 5,968,373, issued to Kyung-Ju Choi on Oct. 19, 1999, in which issued patent ‘there was included spacer filter arrangements to provide a through-flow void space for fractionated distribution of particles between successive spaced layers of filter media so as to maximize particulate holding capacity of an overall filter arrangement.
As noted in above U.S. Pat. No. 5,968,373, it has been long known in the filtration art to separate particulate material from a particulate-laden fluid stream by passing such fluid stream at a given face velocity through a variable density sheet of filter media of a preselected face area with the density of the filter media increasing from the upstream face of the filter media toward the downstream face of the filter media. Or, in other words, the porosity of the filter media has been greater adjacent the upstream face of the media so as to capture the larger size particulate materials from a fluid stream to be treated and to then capture the smaller size particulate materials adjacent the downstream face of the filter media. The prior art also has recognized that such a filtration function can be accomplished with the utilization of successively or immediately layered sheets of filter media, the resulting filter media being of preselected increasing density and of finer or smaller porosity from upstream to downstream face of the layered facing sheets of filter media.
In this regard, attention is directed to U.S. Pat. No. 5,082,476, issued to B. E. Kalbaugh, et al. on Jan. 21, 1992, and U.S. Pat. No. 5,275,743, issued to J. D. Miller, et al, both of which patents teach more recent arrangements of immediate filter media layering, attentions further directed to U.S. Pat. No. 4,661,255 and also as set forth in above U.S. Pat. No. 5,968,373, issued to G. Aumann, et al, on Apr. 28, 1987, and to U.S. Pat. No. 4,732,675, issued to A. Badolato, et al, on Mar. 22, 1988, both of which patents teach multi-layered filter media of varying density but which also fail to recognize the inventive features set forth herein, let alone provide a unique apparatus and method to accomplish the novel arrangement herein described. Further, attention is directed to the additional patents made of record in the above U.S. Pat. No. 5,968,373, which teach additional filter media arrangements but which failed to anticipate the invention of U.S. Pat. No. 5,968,373 and which also fail to anticipate the novel filter media arrangement set forth herein. These additional patents are: U.S. Pat. Nos. 4,322,385, issued to G. W. Goetz on Mar. 30, 1982; 4,589,983, issued to R. M. Wydeven on May 20, 1986; and, 5,858,045, issued to M. J. Stemmer et al on Jan. 12, 1999.
Finally, as in above U.S. Pat. No. 5,968,373, attention is directed to several bullets of interest relating to pore size characteristics: namely, ASTM, Designation F3 16-86, published Apr. 1986 and entitled, “PORE SIZE CHARACTERISTICS OF MEMBRANE FILTERS BY BUBBLE POINT AND MEAN FLOW PORE TEST”; Advances in Filtration and Separation Technology”, Vol. 8, AFS Society pp. 97-99 (1994), entitled, “AIR PERMEABILITY AND PORE DISTRIBUTION OF A DUAL-LAYERED MICROGLASS FILTER MEDIUM”, by Kyung-Ju Choi; Fluid Particle Separation Journal, Vol. 7, No. 1, Mar. 1994 entitled, “PORE DISTRIBUTION AND PERMEABILITY OF CELLULOSIC FILTRATION MEDIA”, by Kyung-Ju Choi; TAPPI 1995 non-woven conference, pp. 44-50, entitled, “PERMEABILITY PORE SIZE RELATIONSHIP OF NON-WOVEN FILTER MEDIA”, by Kyung-Ju Choi; INJ., Vol. 6, No. 3, pp. 62-63, 1994 entitled, “PREDICTION OF AIR PERMEABILITY AND PORE DISTRIBUTION OF MULTI-LAYERED NON-WOVENS”., by Kyung-Ju Choi; and, FLUID PARTICLE SEPARATION JOURNAL, Vol. 9, No. 2, Jun. 1996, pp. 136-146, entitled, “FLUID FLOW THROUGH FILTER MEDIA AT A GIVEN DIFERENTIAL PRESSURE ACROSS MEDIA”, by Kyung-Ju Choi.
The present invention, further recognizing the filtration performance limitations of past filter medium arrangements, as well as the reasons therefore, provides a further unique and novel filter media arrangement involving a novel product and method which does not include the more costly and time consuming selective spacing of past arrangements to further optimize filtration efficiency and capacity of a novel product in an even more straight forward and economical manner than in past filter media arrangements, all being accomplished by the present invention in a straight forward and economical manner, requiring a minimum of additional parts and operating steps to accomplish the same. In effect, the present invention provides a unified filter media product and method of manufacturing the same, which achieves effective particle capture and long life to optimize filtration performance.
In accordance with the present invention, it has been recognized that there is a critical need in the fluid filtration art to provide filtration media with extended life and with finer particle filtration capabilities. In the past and as can be seen in the afore discussion of prior art, to achieve effective particle capture and long filtration life, the multi-layered filter media concept has been generally accepted in the filtration market. To design multi-layered filtration media so as to improve filtration performance, extensive research and development has been required in the past due to the complexity of variables associated with the combination of filtration media layers.
To minimize the research and development, the present invention recognizes and has found it expedient to utilize a comparatively straightforward and novel equation which can be utilized with novel filtration media whether the media is comprised of a single layer of varying face-to-face thicknesses or a plurality of face-to-face layers, each of selected thickness. Given filtration characteristics such as mean flow pore size, pore size distribution, permeability, mean fiber size, porosity defined as pore volume over total volume and dust loading characteristics of individual thickness, filtration characteristics of combined media thicknesses can be calculated in accordance with the present invention by utilizing the unique and novel formula set forth hereinafter. Pursuant to the present invention, selected filtration media characteristics of combined filter media thicknesses—whether the thicknesses are in face-to-face thicknesses in single layer form or in multiple face-to-face layers of thicknesses—which filtration characteristics are superior to the filtration characteristics of individual filter media thicknesses when utilizing the inventive filter media formula hereinafter set forth.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.